Pendulum level indicator



m A N 0 v V W PENDULUM LEVEL INDICATOR Filed Jan. 15,, 1948 William V. Von Am Patented May 22, i951 V a 7 PEN'DULUM LEVEL INDICATOR William V. Von Arx, La Crescent, Minn.

Application January 15, 1948, Serial No. 2,483

2 Claims.

This invention relates to new and useful improvements in level indicators and the primary object of the present invention is to provide an attachment for rods or staffs used by surveyors that will indicate when the rod or staff is disposed in a vertical position or more particularly, in a position perpendicular to the horizon.

Another important object of the present in- Vention is to provide a level indicator attachment for rods and the like including a novel and improved plumb or plumb bob so designed as to eliminate the necessity of having to employ Strings or the like to depend the same in order to determine a vertical position.

A further object of the invention is to provide a mechanical plumb bob attachment for staffs and the like including a novel and improved housing in which the plumb bob is mounted and shielded.

A still further aim of the present invention is to provide a level indicator that is simple and practical in construction, strong. and reliable in use, small and compact in structure, relatively inexpensive to manufacture, neat and attractive in appearance, and otherwise well adapted for the purposes for which the same is intended.

Other objects and advantages reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure 1 is an elevational view of a rod, showing the present invention applied to the same and with parts of the rod broken away and shown in section;

Figure 2 is an enlarged side elevational view of the present invention, and with parts broken away and shown in section;

Figure 3 is a perspective view of the keeper element used in conjunction with the present invention; and,

Figure 4 is a transverse horizontal sectional view taken substantially on the plane of section line 44 of Figure 2.

Referring now to the drawings in detail, wherein for the purpose of illustration, there is disclosed a preferred embodiment of the present invention, the numeral ll] represents a housing generally of any suitable material having an upper wall I2, a rear wall 14, a bottom wall It and a pair of side walls i8 that extend forwardly from the rear wall l4. A window opening is provided in the housing In between the side walls I8, the upper wall l2 and bottom Wall l6. Re-

cessed in vertical notches or grooves 22 provided in the side walls l8 and in horizontal notches or grooves 24 provided in the upper wall l2 and bottom wall It, are the transverse edges 26 and longitudinal edges 28 of a preferably arcuately disposed transparent window 30 that is secured to the walls of the housing In by fasteners or the like 32. It is preferred that an open retaining frame 34 be employed to frictionally engage the outer face of the window 30. This frame 34 is recessed in the grooves 22 and 24 and is'secured to the walls of the housing 10 and the window 30 by the fasteners 32.

Adjustably mounted in an internally threaded, annular opening 35 in the upper wall l2 of the housing, is a pair of externally threaded, coinplementary semi-circular plates 36 and 38 which are provided with opposed concaved recesses, and 42 that frictionally engage a spherical element 44. Also receivably engaging the opening 35, is an externally threaded annular plate 46 having a concaved recess 48 in its lower faceifl which frictionally engages a portion 52 of the spherical element 44 that projects from the recesses 40 and 42. In such a manner, the spherical element-44 is mounted for universal movement in the recesses 40, 42 and 48.

The numeral 54 represents the plumb or plumb bob that is used in conjunction with the present invention generally, comprising a, tapered shank portion 55 the reduced end 58 of which is fixedly secured to the lower periphery of the spherical element 44. Rigidly secured to the larger end 60 of this shank portion 56, is a pointed or conical head 62 preferably of a heavy metallic construction such as brass, whereas it is preferred that the shank portion 56 be constructed of a lightweight metal such as aluminum so that the longitudinal axis of the plumb bob 54 will normally be disposed in a vertical plane or a plane perpendicular to the horizon.

Projecting upwardly from and preferably integrally formed with the bottom wall I8, is a plurality of circumferentially spaced intersecting ribs 64 having raised or pointed central portions 66 to define a central register or indicating point '68 that is adapted to register with the pointed extremity 10 of the head 62 when the longitudinal axis of the plumb bob 54 is in a vertical position.

For the purpose of attaching the present invention relative to a rod or staff 12 that is employed in surveying work, there is provided a base strip or plate 14 that is recessed in one face 16 of the staff 12. Rigidly secured to the plate 14,

is a channel-shaped keeper 18 that opposes and communicates with a key slot or opening 80 provided in the plate 14. Rigidly secured to the rear wall [4 of the housing I0, is substantially T- shaped attaching strip 82 that slidably engages the channel-shaped keeper 18 and slot 80, with the lower reduced end 84 of the slot 80 frictionally engaging the strip 82 to removabl fix the strip 82 relative to the keeper [8.

In practical use of the device, the same may be attached to any type of rod or staff that is used in surveying work and more particularly the same may be used on those types of graduated posts that are used in surveying work for determining the elevation of various prominent terrain features, By the use of such a device, the necessity of having to employ strings or. tapes for depending a plumb bob therefrom in order that the rod may be held in a vertical position will be eliminated. Obviously, the present level indicator may be. quickly and readily removed from the rod on which the same is applied for inspection or service to the parts thereof.

In view of the foregoing description taken in conjunction with the accompanying drawings it is believed that a clear understanding of the construction, operation and advantages of the device will be quite apparent to those skilled in this art. A more detailed description is accordingly deemed unnecessary.

It is to be understood, however, that even though there is herein shown and described a preferred embodiment of the invention the same is susceptible to certain changes full comprehended by the spirit of the invention as herein described and the scope of the appended claims.

Having described the invention what is claimed as new is:

1 An attachment for surveyors sight rods for indicating the vertical position of a sight rod, said attachment comprising a housing having upper and lower walls and a rear wall joining and spacing said upper and lower walls, a plumb bob mounted in said housing, means universally mounting said plumb bob to the upper wall of 4 said housing, a concavo-convexed window having upper and lower curved edges secured to said upper and lower walls and straight rear edges secured to said rear wall, and a plurality of diametrically disposed ribs on the bottom wall of said housing, said ribs having upwardly tapering mid-points, the mid-points of said ribs intersecting to define an indicating point for registry with said plumb bob.

2. In a level including upper and lower walls and a plumb bob mounted on said upper wall for universal movement, a plurality of elongated diametrically disposed ribs on the lower wall, said ribs including central portions tapering toward said upper wall, the tapering central portions of said ribs intersecting each other to define a central indicating point, common to all ribs, for registry with the plumb bob.

WILLIAM V. VON ARX.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 267,655 Vajen Nov. 14, 1882 284,513 Tebar Sept. 4, 1883 444,705 Lambdin Jan. 13, 1891 495,537 Westerman Apr. 18, 1893 723,526 Hein Mar. 24, 1903 918,869 Larsen Apr. 20, 1909 1,097,925 Johnson May 26, 1914 1,265,468 Madsen May '7, 1918 1,328,370 Dutton Jan. 20, 1920 1,639,692 Gauthier 1 Aug. 23, 1927 1,786,184 Woodmansee Dec. 23, 1930 1,827,049 Tenney Oct. 13, 1931 1,869,974 Masters Aug. 2, 1932 2,029,089 Weiruch Jan. 28, 1936 2,128,506 Staunton Aug. 30, 1938 FOREIGN PATENTS Number Country Date 493,686 Great Britain 1938 

